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Mar 19, 2013 8:00am PDT
if this book were hotter? what would it do to the table? energy would cascade from the book to the table until they both became the same temperature and they will level off. so that alcohol that's poured on your back has the same temperature as anything else around, but it feels cold. and why does it feel cold, gang? because what is that alcohol doing? what it's doing is what we're gonna be talking about today. it's changing state. it's changing from the liquid state to the gaseous state, okay? and we call that what? begin with ev? evaporation. evaporation, that's right. and we're gonna be learning that evaporation is a cooling process. you know, sometimes you're swimming and you come out and you're all wet, a little breeze come by and you feel kinda chilly. but if no breeze comes by, you don't feel so chilly. and what's going on? when that breeze comes by, what happens to the water on your body? evaporates. it evaporates. when it evaporates, how does your body feel? begin with a c. - cool. - cool. now, we're gonna ask the question hc. why is it that evaporation is a cooling process? and we ca
Mar 21, 2013 3:00pm PDT
, "you know, i like the energy and the clear thinking that healthy food choice allows." it's still my mantra. "the human condition" is a 26-part series about health and wellness. for more information on this program, and accompanying materials, call: or, visit us online at: narrator: people who exercise regularly have a 43% lower risk of premature death compared to those who are sedentary. are you physically fit? can your body respond to the demands that are placed on it? technology has made life easier, but it has also made us less active. nearly 1/4 of american adults are sedentary. another 1/3 aren't physically active enough to be considered fit. "physically fit" is being able to do whatever you want to do without restriction, either with your body or with endurance. to reach that level of fitness, we need more than just a walk from the parking lot to the mall. we need exercise. thomas mirich: the need for regular exercise transcends not just the need to be able to participate in sports activities, but it really covers the whole gamut from youth 'til 80s, 90-year age group. it's be
Mar 21, 2013 8:00am PDT
is you're getting more energy in the air at nighttime than you are in the day 'cause the sound is being bent. the waves are being bent. we don't say waves bend because one part is going faster than another. we have a name for that. what's it called, gang? - refraction. - refraction. we say the wave is refracted. one part is going faster than the other because of a speed change. what underlies the phenomenon of refraction? some people say, "what? you gotta have a speed change there somewhere." what do you say? begin with y and with p. try it. yup. yup. and that's true. so refraction is a change in the direction of a wave by virtue of a speed change. refraction. sound refracts like this. does that have something to do with the refraction of light? it turns out that anything that we call a wave will exhibit the properties of waves. and one of those properties is refraction. and here, i'm talking about sound refracts. guess what we're gonna talk about later, gang? - light-- - light refracts, okay. we talked about sound interference. later on, we'll talk about light interference. we talk abo
Mar 20, 2013 3:00pm PDT
deep within the earth. their hidden presence may have charged the sacred precinct with spiritual energy. the olmec world was alive with unseen spirits that contrled all natural phenomena. thunder cracks ) rresent the power of these mysterious forces, olmec artists combined features of the most fearsome predators of the jungle, creating hybrid images of awe- inspiring supernatural beings. irual leaders, or shans, lied humans to the fors controinthe uner peleelieved that the sha could slo epraesr shans, and magically transform themselves tohepe oa jaguar transported by thianimal spirit, they road e cosmos gaining knowledge that allowed them to ensure rich harvests, heal the sick and protect the community. rulers also claimed the power to mediate between human and spiritual realms. some are shown cradling a supernatural infant-- part human, part jaguar-- who may have been their link to the spiritual world. similar figures appear on sculptures found at la venta thtirling med to be altars. but decades later, a clue to their true function was discovered far from the coast, at thentainous site
Search Results 0 to 3 of about 4